ARM R4 Manuale Utente
FPU Programmer’s Model
ARM DDI 0363E
Copyright © 2009 ARM Limited. All rights reserved.
12-5
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Non-Confidential, Unrestricted Access
Note
All hardware ID information is privileged access only:
FPSID is privileged access only
This is a change in VFPv3 compared to VFPv2.
MVFR registers are privileged access only
User code must issue a system call to determine the features that are supported.
The following sections describe the VFP system registers:
•
•
•
•
•
12.3.1
Floating-Point System ID Register, FPSID
The FPSID Register is a read-only register that must be accessed in Privileged mode only. It
indicates which VFP implementation is being used.
indicates which VFP implementation is being used.
Figure 12-2 shows the bit arrangement of the FPSID Register.
Figure 12-2 Floating-Point System ID Register format
Table 12-3 shows how the bit values correspond with the FPSID Register functions.
HW
Sub architecture
Variant
Revision
4
Implementer
Part number
31
24 23 22
16 15
8 7
4 3
0
Table 12-3 FPSID Register bit functions
Bits
Field
Function
[31:24]
Implementer
ARM Limited:
0x41
= A
[23]
Hardware or software
0 = hardware implementation
[22:16]
Subarchitecture version
VFP architecture v3 or later with Common VFP subarchitecture v2
a
:
0x02
[15:8]
Part number
0x31
= Cortex-R4F
[7:4]
Variant
0x4
= Cortex-R4F
[3:0]
Revision
See Product revision information on page 1-24 for details of the value of this field.
a. For details of the Common VFP subarchitecture see the ARM Architecture Reference Manual.